if you can't go to the router using 192.168.1.1 try using something like

www.routerlogin.net

it's ultimately the same thing. If it cannot connect then the router is set up wrong/ not properly setup. If the worst comes, going to have to be possibly a fresh win XP install as some viruses could have buggered the whole thing up. I normally install all antivirus and antispyware on before I connect to the Internet. I also get the updates for them from the laptop and save themm onto a CD and update them manually before I connect to the net after a reformat since they are very outdated when freshly installing.

Have you got an ethernet port on your PC? Try doing it through that. Weird as it may seem sometimes it works through ethernet and not through USB and vice versa